1. Field of the Invention
The present invention relates to data print units that print such data as the year, month and day on photographic film, and more particularly it relates to simple, inexpensive, compact data print units applicable to simple non-removable-film cameras generally referred to as throw-away cameras or one-time-use cameras.
2. Related Art
Non-removable-film cameras, comprise one roll of film already loaded in the case, a simple manual film advance mechanism, a simple manual shutter mechanism and a photo lens and do not have a film exchange mechanism that can be easily operated by the user himself. Therefore, their configuration allows only the prescribed number of photographs for the photographic film and does not allow the user himself to replace the photographic film. These non-removable-film cameras can be purchased inexpensively for a price only slightly higher than the single-unit price of the photographic film. For this reason, they can be referred to as "lens-equipped film." This makes them easy to use when you do not have your own camera on trips or at events. Some of these non-removable-film cameras are equipped with a flash device as in regular cameras, but there are none with a data print device that prints data such as the year, month and day on the film. There is a limit to the number of pictures a non-removable-film camera can take, and the period during which they can be used is also limited, but there is a strong demand to be able to leave data on each photograph to facilitate their arrangement.
There are many cameras such as 35 mm twin lens reflex and single lens reflex cameras that are equipped with a data print device (camera module). This data print device is mounted behind a photographic film 2 inside a back cover 1 of the camera as shown in FIG. 36, for example, and it exposes the year-month-day data number string on the back of photographic film 2. The data print device comprises a resin case that is approximately 3 cm square and 3 mm thick, a photodiode or tungsten lamp housed inside the resin case as a light source 3a, a reflecting mirror 3b that reflects the light beam, which is emitted from light source 3a and travels along the surface of the case, at a fight angle so that it is deflected in the direction of the thickness of the case, a transmission type liquid crystal display element 3c illuminated by the reflected light, and a shielding plate 3d that restricts the illumination on the display element, whereby the transmitted light formed in the shape of a data number string by the transmission type liquid crystal display element 3c is projected on the rear surface of photographic film 2 as parallel beams of light. The print data number string is formed by freely changing the multiple-digit number for the year-month-day displayed on the transmission type liquid crystal display element 3c by changing the data signal of the liquid crystal driver by an external operation, and therefore there is no restriction on the year-month-day data that is printed.
It is possible to apply such a data print device (unit module) for cameras to non-removable-film cameras, but the high cost of the transmission type liquid crystal element 3c, driver IC and other electronic parts would nullify the cost advantages of non-removable-film cameras. Therefore, a data print device that can be practically used with non-removable-film cameras must be simple and inexpensive. Since the function of transmission type liquid crystal display element 3c is to shape the illumination light into the form of data light and project it, the inventors realized that a print data plate with translucent year-month-day data sections, for example, could be used instead of this transmission type liquid crystal display element and proposed a configuration in which the appropriate print data number could be selected by manually turning the data plate.
In this case, the restricted surface area naturally limits the amount of data in the data sections (year-month-day) that can be displayed on the print data plate, but since there need only be sufficient data for the limited period during which the non-removable-film camera can be used, it is only necessary to be able to select year-month-day data for a fixed period. However, it is necessary to mount a print data plate with updated data in print devices for differing use periods. Therefore, the print device must have a structure that facilitates attachment and removal of the data plate.
However, even if a simple, inexpensive configuration is realized by employing a data print device equipped with a print data plate, the structure of the non-removable-film camera, which is the main unit, requires that this device have a compact configuration (e.g., approximately 3 cm square and 3 mm thick).
Although conventional print devices allow electronic static operation of data selection, since the print data plate is movable, a configuration must be used that sufficiently considers play, etc., of the print data plate. This is because if the print data plate should rotate eccentrically, have play or become warped, the transmitted light that passes through the data sections will become diffused, resulting in deformation, dropout or fuzziness of the data numbers exposed on the film, thus degrading exposure quality. In spite of this problem with exposure quality, a data selection mechanism is necessary in the data print devices that use this kind of movable mechanism. That is, the selection of a specific data section requires that the print data plate be rotated to a specific position and that it be held stationary at that position.
For the purpose of realizing a low-cost, compact data print device suitable for non-removable-film cameras, the first objective of the invention is to offer a data print device that facilitates the attachment and removal of the print data plate, the second objective is to realize a structure that prevents eccentric rotation, play or warping of the print data plate, and the third objective is to realize a data selection mechanism suitable to the print unit.